Boat trailer guiding devices for use in launching and later retrieving boats are, in general, known. An example of such a device is described in U.S. Pat. No. 4,197,050, issued Apr. 8, 1980, to Larson, which exemplifies an apparatus for centering the hull of a boat on a boat trailer during launching and loading of the boat. The assembly includes, inter alia, upwardly directed resilient tubes which are used to guide the hull as the boat is moved. The tubes are generally fixed, remaining substantially vertical at all times. U.S. Pat. No. 4,011,958, issued Mar. 15, 1977 to Carrick and U.S. Pat. No. 4,623,161, issued Nov. 18, 1986 to Sprague describe similar devices.
Boat trailer guiding devices have also been developed which include movable upwardly directed tubes or arms. Examples of such devices are disclosed in U.S. Pat. No. 4,529,217, issued July 16, 1985 to Wood and U.S. Pat. No. 3,447,815, issued June 3, 1969 to West. In each case, movement of the upwardly projecting arms (which act as guides) is from side to side. Devices of this design tend to remain substantially vertical at all times. The side to side motion of the guide arms usually requires the trailer to be some distance away from the dock to facilitate such movement.